Method of separating meat components via centrifuge

ABSTRACT

A centrifuge has an inner and an outer screw. The outer screw transfers material towards a cone-shaped section that leads to an outlet of the centrifuge. A mixture of meat components, liquid carbon dioxide, gas, and optionally water, is spun in the centrifuge. The dense components, such as lean meat, will accumulate away from the axis of rotation and be transferred by the outer screw towards the cone-shaped section. The less dense components, such as fat and adipose tissue, accumulate toward the center of rotation, and are transferred toward an outlet of the centrifuge via the inner screw. Gas accumulates in the proximity of the cone-shaped section and impedes liquid carbon dioxide from exiting with the dense components. The centrifuge is pressurized, which maintains carbon dioxide as a liquid.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/720,594, filed Apr. 30, 2009, which is the U.S. national stage entryof International Patent Application No. PCT/US2005/043507, filed Dec. 2,2005, which is a continuation-in-part of U.S. patent application Ser.No. 11/004,669, filed Dec. 2, 2004, and claims the benefit of U.S.Provisional Application No. 60/639,828, filed Dec. 28, 2004. Allapplications are incorporated herein expressly by reference.

FIELD OF THE INVENTION

The present invention relates to the separation of meat components via acentrifuge.

BACKGROUND

In the process of boning a carcass, the external fat layer is removed.During this process, a significant amount of lean meat can be cut fromthe carcass and discarded with the fat. This process leads to asignificant loss of lean meat. To recover the lean meat, the discardedfat was heated and processed in a centrifuge to separate the fat fromthe lean meat. The lean meat was then frozen and chipped into smallflakes. The finished product, known as Lean Finely Textured Beef(hereinafter “LFTB”) could later be added to ground beef, for example.The temperature of the LFTB during the separation process is not highenough and long enough to kill bacteria. As a result, pathogens andbacteria that are present on the surfaces of the carcass prior to boningcan result in bacteria being present in the LFTB.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features ofthe claimed subject matter, nor is it intended to be used as an aid indetermining the scope of the claimed subject matter.

A “Decanter Style” centrifuge has a horizontally disposed tubular shapedrotating “bowl” with a cone-shaped section enclosing each end of thetube shaped “bowl” at each end. An inner and an outer screw are mountedcentrally, in horizontal disposition within the “bowl”. The inner screwtransfers material towards one of the cone-shaped sections that leads toan outlet of the centrifuge. A mixture of temperature controlled groundmeat (for example beef), temperature controlled liquid phase and gaseousphase and/or vapor phase carbon dioxide, gas, and water, is loaded intoand then spun within the centrifuge. The higher density components, suchas lean (muscle) meat, will accumulate against the inner surface of thespinning “bowl”, away from the central axis of bowl rotation and is thentransferred by the outer screw towards a cone-shaped section. The lowerdensity components, such as fat and fatty adipose tissue, accumulatetoward the center of rotation, and are transferred toward an outlet viathe inner screw. Gaseous phase carbon dioxide accumulates in the centerof centrifuge, closest to the axis of rotation and in proximity of thecone-shaped section. The lean meat and fat are transferred out throughnarrow conduits, while the gas stratum displaces liquid carbon dioxidefrom the conduits through which they are removed, which cansubstantially reduce the loss of any liquid carbon dioxide. Thecentrifuge is pressurized at a pressure, such as about 550 psig, whichcan maintain carbon dioxide as a liquid at about 34 degrees F.Additionally, pressurized and temperature controlled carbon dioxide withwater forms carbonic acid which can kill bacteria and pathogens.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same become betterunderstood by reference to the following detailed description, whentaken in conjunction with the accompanying drawings, wherein:

FIG. 1 illustrates a centrifuge to separate meat in accordance with oneembodiment of the present invention;

FIG. 2 schematically illustrates a heat exchanger assembly in accordancewith one embodiment of the present invention; and

FIG. 3 illustrates a single plate of a plate heat exchanger.

DETAILED DESCRIPTION

FIG. 1 is a diagrammatic representation of a cross section through acentrifuge in accordance with one embodiment of the present invention.The centrifuge 1000 includes a housing 186 (the “bowl”). The housing 186is generally horizontally disposed and cylindrical in shape withcone-shaped sections enclosing a space therein. The housing 186comprises a cylindrical shaped “bowl” with a first cone-shaped section109 at one end of the housing 186. A second cone-shaped section 125 islocated at a second and opposite end of the “bowl”. The cone-shapedsection 109 tapers down in diameter from that of the housing 186 to asmaller diameter defining a cylindrical conduit section 195. Section 195leads to a manifold, which is ultimately connected to outlet 199.Similarly, the cone shaped section 125 tapers down in diameter from thatof the housing 186 to a smaller diameter defining a cylindrical conduitsection 137. Section 137 leads to a manifold section 165, which isconnected to the outlet 132. The cone-shaped section 125 has an inwardlyfacing beach face at 171 within the interior thereof. The beach face at171 encloses an annular space created between the beach face 171 walland the outer vessel wall at 125. The annular space communicatesdirectly with annular space 168 enclosed within conduit section 138which connects directly with manifold 165 and then to outlet 132. Thebeach face 171 has ports 126, 170 that allow fluid material comprisingsubstantially liquid phase carbon dioxide to be removed from thecentrifuge 1000 via the outlet 132. The cone-shaped section 109 is inclose and near contacting relationship with an outer screw. The coneprofiled beach face 171 is in close and near contacting relationshipwith inner screw 174. The inner beach face of cone-shaped section 109 isprovided to enable extraction of matter such as lean beef, thataccumulates against the inner face of cylindrical housing 186 by therotating action of outer screw 120, whereas beach face at 171 isprovided to enable the extraction of matter, such as beef fat, afteraccumulation within the space defined by broken lines 122 and 128,through the conduit 138, and discharged from outlet 160. It is to beappreciated that the use of the terms “lean meat” or “fat” aregeneralized definitions, in the sense, that “lean meat” may contain somefat, but the lean meat is the predominant component. Similarly, the term“fat” is generalized to mean material wherein fat is the predominantcomponent, but it may include some lean meat.

It can be seen that the centrifuge sections 195, 109, 186, 125, and 137,are connected together to provide a single pressure vessel, which isconfigured to rotate as a single enclosed sealed and pressurized unit.Bearings support the pressure vessel 1000 which enable the unrestrictedrotation thereof. The pressure vessel 1000 is supported by bearings 100,102, 198, 138, and 164, and bearings at 166 and 144. All bearings aresealed to prevent escape of carbon dioxide gas or other fluids. Thecentrifuge assembly 1000 is driven by surface drive wheels 104 and 202,and drive wheels 131 and 163. Drive wheels 112 and 178 are disposed atabout the middle of the centrifuge 1000. Drive wheels rotate thecentrifuge at approximately 500 rpm. The centrifuge 1000 includes acentral shaft 108 which is supported by bearings 100 and 144 atrespective ends thereof that permit shaft 108 to rotate. Bearings 100and 144 also seal the central shaft 108 against gas or liquid seepage.The shaft 108 can have a hollow core providing a conduit 99 through thecenter of the shaft 108. The shaft 108, therefore, provides an inlet fora gas to be injected within the interior of the centrifuge 1000. Forexample, any gas, including carbon dioxide, carbon monoxide, any noblegas, or gas combinations, can be injected through the hollow core 99 ofthe shaft 108. The gas exits within the centrifuge 1000 throughapertures 204 disposed in the shaft 108 at about the center of thecentrifuge 1000. In one embodiment, the shaft includes spirals(Archimedes screws). However, other embodiments may include paddles, orother means for transferring material, such as conveyors, etc. The shaft108 includes an inner spiral 174 and an outer spiral 120. The outerspiral 120 transfers matter accumulated against the interior surface ofthe housing 186 and transfers the matter toward the cone-shaped section109, through the narrow cylindrical conduit 195, and is then dischargedthrough outlet 199. The outer spiral includes the spiral section 120,which has a diameter approximately equal to the inside diameter of thehousing 186. However, the individual flights in the spiral section 120are not attached to shaft 108, but nevertheless, form a continuousspiral. The outer spiral section 120 is connected via a transitionspiral section 121 at the cone-shaped section 109, which does haveindividual flights connected to shaft 108, but decrease in diameter inconformance with the cone-shaped section 109. The transition spiralsection 121 connects to a smaller diameter spiral section 106 in thecylindrical section 195. In this manner, it can be appreciated thatmaterial that accumulates in against the interior surface of housing 186in zone 119 will be transferred toward the cone-shaped section 109 andis eventually discharged through the outlet 199 as indicated by thedirection of arrow 196. The inner screw or spiral includes the leftspiral section 188, which is located within the outer spiral section120. The inner spiral includes the right spiral section 174, which isalso located within the outer spiral section 120. The spiral section 174has flights that decrease in diameter in proximity to beach face 171,which transitions to even smaller diameter flights within thecylindrical section 138. In this manner, material that accumulatestoward the center axis of the centrifuge 1000, such as at stratum 193,will be transferred toward the cone-shaped section 125, through narrowedconduit 138, and eventually discharged from outlet 160, as indicated bythe arrow 158. In one embodiment, the inner spiral sections may have aleft hand spiral, while the outer spiral sections may have a right handspiral, or vice versa. In another embodiment, both the inner spiral andthe outer spiral can have the same direction. In the latter case, theinner spiral and the outer spiral can be driven independently of oneanother in opposing directions, so as to cause material to betransferred in two directions. In the former embodiment, both the innerspiral and the outer spiral can be disposed on a single shaft, asillustrated. Thus, the rotation of the shaft 108 will cause material tobe transferred in opposing directions by the inner spiral and the outerspiral, and out through respective outlets in accordance with whetherthe material is a dense material or a less dense material.

More particularly, a planetary gear arrangement can be provided so as toconnect the housing 186 and shaft 108 through a planetary geararrangement having a ratio such that the screw assembly will rotaterelative to the housing 186 at a speed sufficient to transfer stratifiedmaterials from within the centrifuge at a suitable rate approximatelyequal to the rate of mass flow of goods transferred into the centrifuge.

The right side of the shaft 108 also has a hollow core forming theconduit 130. In the illustrated embodiment, the conduit 130 is incommunication with a cone-shaped vessel 146. The vessel 146 is locateddownstream from a meat grinder plate 148. The meat grinder 148 is drivenby a shaft 200, which is connected to a driver (not shown). The meatgrinder 148 is fed through inlet 150, as indicated by arrow 152. Liquidcarbon dioxide, and optionally water, is introduced into vessel 146 viaconduits 142 and 156, as indicated by arrows 136 and 154. Liquid carbondioxide and ground meat combine in the cone-shaped vessel 146, whichleads to the conduit 130. Material travels through conduit 130 andeventually exits into the interior of the centrifuge housing 186 at adistributor 184 via the outlets 116 and 182. Ground meat will becomposed of particulate materials, including lean meat, fat tissue, andadipose fat tissue. Pressure and temperature are controlled within thecentrifuge housing 186 to maintain carbon dioxide in the liquid state.However, gas, such as carbon dioxide gas, is also present within thehousing 186 of the centrifuge 1000. The gas is introduced via theconduit 99 from the left side of the shaft 108. The mixture, includingground meat comprising lean meat and fat, liquid carbon dioxide, gaseouscarbon dioxide, and optionally water, is centrifugally spun within thehousing 186 of the centrifuge 1000. In one embodiment, the temperatureof the carbon dioxide gas introduced via conduit 99 may be elevated toabout 100 degrees Fahrenheit so that the density of the gas will besubstantially lowered. The object is to reduce the amount of carbondioxide that is used in the centrifuge for cost savings.

Through centrifugal force created by rotation, stratification ofmaterials within the centrifuge 1000 is produced. The most densecomponents, such as heavier lean meat, will accumulate on the interiorside of the housing 186, in the strata defined by the dotted line 105.These denser components are transferred via the outer screw 120 towardsthe cone-shaped section 109, through the narrowed section 195, andeventually out through the conduit 199. Generally, the component with adensity below that of lean meat will be liquid carbon dioxide. Liquidcarbon dioxide will generally accumulate as a stratum defined betweenthe dotted lines 105 and 122. Liquid carbon dioxide may exit through thebeach face 171 at the cone-shaped section 125 through apertures 126 and170 in the beach face 171, which are at a height of the stratum definedbetween the dotted lines 105 and 122. The liquid carbon dioxide passesbetween the beach face 171 and the outer housing through the annularspace 168, defined by the outer wall of conduit 138 and the inner wallof conduit 137, eventually leaving the centrifuge 1000 through outletconduit 132. Conduit 132 is connected to a system for chilling thecarbon dioxide, as discussed below, so as to enable recycling of liquidcarbon dioxide. Generally, lower in density than liquid carbon dioxidewill be fat and adipose tissue. Fat will generally accumulate in astratum defined by the dotted lines 122 and 128. This material will betransferred via the inner screws 188, 174 towards the beach face 171,and below the apertures 126, 170 to minimize transfer out with liquidcarbon dioxide, through the narrowed conduit 138, and is dischargedthrough outlet 160. The least dense component will generally be any gas,such as carbon dioxide, carbon monoxide, any noble gas, or combinationsof gas. Such gas accumulates in a stratum defined by the dotted line113, and will fill the volume surrounding the central axis of thecentrifuge. The outer boundary 113 of the concentric stratum of gas willgenerally need to be kept greater than the diameters (i.e., theperimeters) of the narrowed conduit 195 and the narrowed conduit 138 inorder to displace the liquid carbon dioxide that tends to mix with thelean meat, as the lean meat passes through the stratum of liquid carbondioxide in its path down the cone-shaped section 109. Note too, that theouter screw 120 has individual spiral flights that are about thethickness of the stratum of lean meat, which avoids also transferringliquid carbon dioxide with the lean meat. Such concentric layer of gasextends in thickness past the openings leading into the narrowedconduits 195 and 138. Such gas occupies the central concentric volumewithin the housing 186 bounded by the dotted line 113. As can beappreciated such boundary 113 extends beyond the diameter of thenarrowed section 195 through which the lean meat is transferred. Becausethe gas occupies the central volume of the centrifuge 1000, the gas actsas a barrier by displacing liquid carbon dioxide with gas, which iscarried with the most dense component, i.e., the lean meat, via section195 and conduit 199. As can be appreciated from the foregoingdescription, the centrifuge produces concentric zones of stratificationbased in order of decreasing density toward the central axis, whereinthe most dense components accumulate next to the interior surface of thehousing 186, and the least dense components being at the center of thecentrifuge.

Operation of the centrifuge to separate meat components into lean andfat is based on the density differences between components. The carbondioxide fluid will be pressure controlled, preferably from 400 to 560psig, more preferably from 440 to 520 psig, or even more preferably from460 to 500 psig, with a suitable pressure being about 480 psig, suchthat the density of carbon dioxide is less than the density of the leanmeat and greater than the density of the fat. The density of the liquidcarbon dioxide being from 45 to 65 pounds per cubic foot, preferablyfrom 50 to 60 pounds per cubic foot, and more preferably from 52 to 58pounds per cubic foot. Changing the density of the liquid carbon dioxideis believed to affect the separation efficiency. The housing 186 isrotated by a variable speed motor, such as an electric or hydraulicmotor, which is attached thereto in such a manner that enables therotating of housing 186 at a controlled speed (revolutions per minute),such as at from 300 rpm to 1000 rpm, with 500 rpm being suitable, but,preferably at such a speed (rpm) that will cause an artificial increasedgravitation field to be applied to the carbon dioxide fluid and groundmeat transferred into housing 186.

Variable speed positive displacement pumps are connected directly to allinput and output conduits connected to the interior of the centrifuge1000, in such a way that pressure can be maintained within thecentrifuge. Pumps transferring ground meat and carbon dioxide viaconduit 130 are controlled to provide a selected input combined massflow while extraction positive displacement pumps are connected tooutput conduits so as to enable the extraction of processed materials,such as liquid carbon dioxide via outlet 132 to be cleaned and recycled,fat via outlet 160, and lean meat via outlet 199. The pressure withincentrifuge 1000 is controlled such that the density of the fluid carbondioxide is maintained at a selected value, such as 45 to 65 pounds percubic foot, preferably about 57 pounds per cubic foot. The materialstransferred into centrifuge 1000 are also maintained at a selectedtemperature, which can be adjusted by adjusting the pressure. Beeftransferred into centrifuge 1000 can be maintained at a pressure ofabout 500 psig to about 2000 psig.

The housing 186 is manufactured from stainless steel, carbon steel orany other rigid material capable of withstanding the pressure rangesdescribed herein. The diameter of housing 186 may be in the order of 30inches and is rigidly attached at each end to cone-shaped sections eachtapering and connecting to conduits having a smaller diameter thanhousing 186 and parallel thereto. The dotted lines 113 and 181 define acentral annular, volume 110 which can be filled with pressurized carbondioxide gas having been transferred therein via conduit 108 at apressure, such as about 480 psig, such that when lean meat istransferred across the internal beach face of cone-shaped section 109,the dense fluid (liquid) carbon dioxide which occupies the annular spacedefined by dotted lines 105 and 122 is not carried with the lean meatand is displaced by gaseous carbon dioxide in such a way that the leanmeat (beef) transferred into and through conduit 195 does not carryexcessive quantities of carbon dioxide therewith.

The annular space defined by and between dotted line 105 and 162 and theinternal face of housing 186 shows a fraction of the internal space ofhousing 186 where the most dense material, i.e., lean meat, such as leanbeef will accumulate; the dotted lines 105 and 122 define the boundariesof an annular space wherein fluid and/or liquid carbon dioxide will tendto accumulate and the annular space defined between dotted lines 122 and113 comprises the annular space in which the least dense ground meat fatcomponent will accumulate after centrifuging therein. After or duringcentrifuge separation, materials will be removed from the centrifuge1000, as discussed above.

The centrifuge shown in FIG. 1, including housing 186, cone-shapedsection 109, conduit 195, and cone-shaped section 169 with conduitsection 137, are rigidly connected to provide a sealed and gas tightvessel, which is located and held captive by variable drive wheels 104,202, 112, 178, 131, and 163, which rotate the centrifuge vessel 186 atspeeds to produce a separating force equal to as much as 3000 G, whereinone (1) G is the equivalent of the gravitational force at the surface ofthe earth. However, when used in applications to separate beef fat frombeef lean, the speed of the rotating centrifuge may be limited to just afew hundred rpm, exerting a centrifugal force on the materials in theorder of a few hundred G or even substantially less. A relatively low Gforce on the order of 30 to 100 G can provide sufficient force toquickly separate beef adipose fat from lean beef, maintained at atemperature of approximately 32-34 degrees F. The pressure withinhousing 186 is controlled and adjustable from 300 psig to 1100 psig, butpreferably is at about 480 psig (and at a temperature of about 38° F.).The total rate of volume flow, for example, can be about 250 gallons perminute (gpm), and a similar quantity of material can be extracted.

A positive displacement pump is connected to conduit 199 to transferlean meat at a controlled rate proportional to the ground meat beingtransferred into the housing 186. Ports 126 and 170 in beach face 171 inthe cone-shaped section 125 allow surplus liquid carbon dioxide to betransferred through annular space 168 into annular manifold 165 andthrough conduit 132. Conduit 132 is connected to a pressure and massflow controlling, second positive displacement pump. A third pressureand mass flow controlling, positive displacement pump is connected toconduit 160 such that fat can be extracted from centrifuge 1000. First,second and third positive displacement pumps (not shown) respectivelyconnected to conduits 199, 132 and 160, are controlled via a centralcomputerized controlling system in such a manner that goods transferredby controlled variable speed positive displacement pumps through grinder148 plus liquid carbon dioxide transferred through conduits 156 and 142,which are also transferred by positive displacement pumps, aresubstantially of equal mass and balanced with the materials beingextracted by pumps connected to conduits 199, 132, and 160, such thatthe mass of materials pumped into housing 186 are substantially equal tothe mass of materials pumped from housing 186. Additionally, asdiscussed above, conduit 108 provides a means of injecting gaseous phasecarbon dioxide into centrifuge 1000, via apertures 204. As discussedabove, gaseous carbon dioxide minimizes the quantity of liquid carbondioxide that is lost from the centrifuge 1000 with the lean meat.Gaseous phase carbon dioxide or any other gas, such as nitrogen and/or ablend of carbon dioxide may include carbon monoxide, wherein the carbonmonoxide content is not more than about 0.4% by volume (or weight).Accordingly, by centrifugally spinning the mixture of ground meatcontaining fat components and lean meat components, the fat accumulatingat zone defined by lines 122 and 113 can be transferred from thecentrifuge 1000 via conduit 160 by rotating the Archimedes screwassembly, simultaneously, lean meat accumulating in spaces 176 and 119is transferred through conduit section 195 into space 106 and dischargedvia conduit 199. Liquid carbon dioxide is extracted via conduit 132 inthe direction of arrow 134. Liquid carbon dioxide extracted via conduit132 can be recycled after sanitizing, filtering and adjusting so as tomeet pressure and temperature settings, and reintroduced into conduits142 and 156.

The centrifuge disclosed herein provides for the separation of twosolids (i.e., fat and lean beef) and one liquid (liquid carbon dioxide),wherein the liquid (carbon dioxide) is a gas at ambient atmosphericconditions. In this way, the liquid carbon dioxide can be used as anagent facilitating the separation of the two solids (fat and lean beef)and after use of the liquid for this purpose, the liquid evaporatesleaving no residue with the solids.

Referring now to FIG. 2, a diagrammatic representation of a plan view ofprocessing equipment intended for use in the separation of fat and leanbeef from ground beef in accordance with one embodiment of the presentinvention is shown. The apparatus shown is arranged to facilitate therecycling of liquid carbon dioxide, used in the centrifuge separationprocess. A rigid steel frame 9 is shown with a “bowl” 8 wherein, “bowl”is a term used in industry to describe the horizontal (or vertical)member which is driven by a variable motor, such as an electric orhydraulic motor, such that it rotates about an axis. The bowl 8, mountedonto frame 9, is an apparatus similar to that which is represented byFIG. 1, with the changes as noted herein. A refrigeration unit 21 withcondenser 49, which may be an R22 chiller (or even liquid carbondioxide, is arranged to chill recycled fluid, such as 50% propyleneglycol, or brine, to a temperature of about 25° F., wherein brine caninclude any fluid, such as glycol or water and ethanol or any blend offluids. The recycled fluid is transferred via conduit 27 in thedirection shown by arrow 34 to a plate heat exchanger 30 mounted uponframe 31, which may comprise a rigid steel weldment or steel casting.After absorbing heat from a relative hot fluid, the fluid is thenreturned in the direction shown by arrow 29 via conduit 26 to therefrigeration unit 21. The refrigeration unit 21 includes a heatexchanger enabling the controlled temperature reduction of the recycledfluid, which can be pumped there through at a controlled mass flow ratewherein the temperature of the fluid may be reduced to 25 degrees F. Theplate heat exchanger 30 is arranged with a series of steel plates andsuitable sealing means, such as “O” rings. The term “plate heatexchanger” is used in industry to describe a special type of heatexchanger which can be opened to enable cleaning. In a plate heatexchanger, any number of plates and sealing means (“O” rings) can bearranged in a sandwiched arrangement with each plate in verticaldisposition, parallel and “in line” with each other plate and alsoarranged to slide horizontally along retaining shafts rigidly attachedto frame 31. Retaining shafts are arranged such that steel plates can beopened and spread apart from each other enabling the cleaning of eachplate on both sides. The construction of the plate heat exchanger 30with frame 31 can be more readily understood with reference to FIG. 3,wherein a full side view elevation is shown. A rectangular steel plate42 with vertical edge 36 and horizontal edge 33 is shown with fourapertures 39, 37, 43, and 40 arranged wherein each aperture is locatedat a corner of the rectangular plate 42. The purpose of the plate heatexchanger 30 is to enable the temperature control of any fluid, forexample, the liquid carbon dioxide from a centrifuge, which may containa food or fat component or particles of protein wherein the particlescan contact, adhere and become bonded to the heat exchange surface. Twofluids, one “cold,” one “hot,” are processed simultaneously with theplate heat exchanger. The cold fluid, such as 50% glycol, is recycledthrough the refrigeration unit and passes on one side of the plates inthe plate heat exchanger 30. The hot fluid passes on the side of theplates that are opposite of the cold fluid. The hot fluid releases heatacross the plates and the heat raises the temperature of the cold fluid,thereby driving the temperature of the hot fluid down and thetemperature of the cold fluid up. The plate heat exchange 30 can be aco-current or counter-counter exchanger. Pressure, flow and temperaturemeasuring devices, are located at any one or more of the inlets andoutlets of the plate heat exchanger 30, from which readings the flow,pressure or temperature of one or both fluids can be controlled. Anystyle of heat exchanger may be used, including, for example, a shell andtube heat exchanger, however, in this instance, a plate heat exchangeris illustrated.

Steel plate 42 shown in FIG. 3 is profiled with a series of depressionsformed in continuous channels 44 and a sealing mechanism, such as an “O”ring, is located in a corresponding “O” ring groove, such that aselected quantity of steel plates can be pressed and clamped together ina sealing manner with “O” ring seals located between each plate.Multiple steel plates similar to the single steel plate shown as 42 inFIG. 3 are stacked in a sandwiched arrangement, wherein the two oppositefaces of each plate are in contact with a face of an adjacent plate toprovide a group of plates, which are then clamped together such that onefluid can be transferred along the channels on one side of each plate,and the second fluid is transferred along the channels on the oppositeside. Thereafter, plates can be added or removed to adjust the totalsurface area available for heat transfer. In one embodiment, the steelplates are arranged such that the cold fluid recycled along conduits 27and 26 and through refrigerated heat exchanger 21 can enter at aperture37 and exit at aperture 40. Aperture 37 can be connected to conduit 27in FIG. 2 and aperture 40 in FIG. 3 can be connected to conduit 26 inFIG. 2. In this way, temperature controlled cold fluid transferred viaconduit 27 can travel by reticulation along the channels in each steelplate and across the surface of the plate and then through aperture 40and into conduit 26 to be returned to refrigeration unit 21. The coldfluid can be at a temperature such as 24 degrees F. Hot fluid, such asliquid carbon dioxide, can be transferred in the direction shown byarrow 12 through conduits 45 and 35 into steel plate heat exchanger 30between opposite sides of the steel plates and then through conduits 32and 18 in the direction shown by arrow 22. Liquid carbon dioxide can,therefore, be cooled. Liquid carbon dioxide may be cooled from 0° F. to66° F., from 26° F. to 36° F., preferably, 28° to 34° F., and even morepreferably 30° F. to 32° F. Conduit 35 corresponds and connects directlywith aperture 39 shown in FIG. 3 and conduit 32 corresponds directlywith aperture 43 in FIG. 3. Conduit 45 is a feed line to plate heatexchanger 30 and conduit 32 is a return line from plate heat exchanger30 for liquid carbon dioxide used in the centrifuge separation processof the apparatus of FIG. 2. Conduit 45 is connected directly to manifold2 (FIG. 2) such that fluid extracted from bowl 8 is run through theplate heat exchanger 30 and cooled and is returned to bowl 8 throughmanifold 48 (FIG. 2).

Referring briefly to FIG. 1, apertures 126 and 170 are provided in thebeach face 171 of the cone-shaped section 125. Apertures 126 and 170connect to annular conduit 137 enabling the extraction of liquid carbondioxide from zone 118 through annular space 168 and into manifold 165,which connects to conduit 132. Similar apertures, beach face, annularspace, manifold and conduit may be provided at the opposite end ofvessel 186 at the cone section 109, but are not illustrated. In thisway, liquid carbon dioxide could be withdrawn from conduit 132, andafter chilling in the plate heat exchanger 30 (FIG. 2) can be introducedinto housing 186 at the opposite end from conduit 132. This has theadvantage that the consumption of carbon dioxide for the purpose ofchilling ground beef is reduced and can be minimized to provide improvedeconomy.

Referring again to FIG. 2, ground beef blended with a controlledproportion of liquid carbon dioxide having a ratio of 1 part ground beefor less to 1 part liquid carbon dioxide or less, or alternatively,having any ratio of liquid carbon dioxide to ground beef content, can betransferred into conduit 47 in the direction shown by arrow 16.Preferably, the temperature of the ground beef will be determined andthen adjusted to meet the temperature of the carbon dioxide liquid withwhich it will then be blended. Such temperature adjustment can beachieved by compensation wherein lowering the temperature of the liquidcarbon dioxide is facilitated to such a degree that after blending withthe beef, the “averaged” temperature of the blend will be equal to therequired temperature, e.g., 34 degrees F.

Liquid carbon dioxide can be introduced into manifold 48, which in turnconnects with bowl 8, and ultimately can be extracted from manifold 2. Aquantity of water may also be blended with liquid carbon dioxide andtransferred into bowl 8 via manifold 4. Water making up about 2% byweight, can be blended with the carbon dioxide prior to blending theresultant mixture with ground beef in proportions that will result in ablend of carbon dioxide, beef, and water to compensate for any moisturethat will be lost due to hydration of the carbon dioxide gas that mayultimately boil off into the atmosphere after extraction from thecentrifuge. Water may be about 1% to 3% by weight (or volume) of thequantity of beef blended with the carbon dioxide (and water). Fatseparated from ground beef in a manner as described in connection withFIG. 1 can be extracted via manifold 46. Lean beef separated from groundbeef in a manner as described in connection with FIG. 1 can be extractedfrom conduit 1. Cone-shaped ends 7 and 10 are arranged in similar mannerto cone-shaped sections 109 and 125 in FIG. 1. Bearings 11 and 51 areprovided to enable the precise and unrestricted rotation of bowl 8 withconcentric conduits 1, 41, and 5 at one end, and 47, 17, and 12 at theopposite end of bowl 8. The operation of centrifuge apparatus shown inFIG. 2 with bowl 8 can be arranged so as to operate similarly to bowl186 as shown in FIG. 1; however in FIG. 2 two additional manifolds 2 and4 are shown. Lean meat separated from ground beef transferred intoconduit 47 is extracted from conduit 1. Fat separated from ground beeftransferred into conduit 47 can be extracted via manifold 46.Temperature controlled liquid carbon dioxide having been treated inplate heat exchanger 30 (FIG. 2) with refrigeration unit 21 can betransferred into bowl 8 via conduit 48, and an equal quantity of liquidcarbon dioxide can be extracted from the bowl 8 via conduit 2.

Referring to Table 10 below, properties of saturated carbon dioxideliquid and/or vapor are shown in units of pressure (psi), temperature(degrees F.) and density (lbs/cu. ft.) Carbon dioxide at a temperatureof 0 degrees F., for example, as shown in row 2, will have a density of63.64 lbs/cubic foot at 305.8 psia. Row 3 shows the data for carbondioxide at 28 degrees F., which has a density of 58.78 lbs/cubic foot. Atotal of 13 sets of data are shown for carbon dioxide at temperatureswith the corresponding pressure and density values. Fluid carbon dioxidecan be provided at any temperature, pressure and density described. Forexample, fluid carbon dioxide may be provided into the centrifuge shownin FIGS. 1 and 2 adjusted to a temperature of 30 degrees F. and at arate of approximately 100 gallons/minute, in which case, the pressureand density would be as shown in row 4. Carbon dioxide extracted viamanifold 2 may have a temperature of about 36 degrees F., and at 36degrees F. and at a pressure of 521.3 psig, the density will be 57.12lbs/cubic feet as shown in row 7. The apparatus shown in FIG. 2 and FIG.3 includes a refrigeration and plate heat exchange system enabling fluidcarbon dioxide extracted at 36 degrees, for example, from manifold 2 tobe pressurized and chilled to, for example, 30 degrees F., with thepressure and density as shown in row 4. The input temperature andextraction temperatures may be at any selected temperature shown in rows2 through 14 with the corresponding other properties also shown in eachrow. Gaseous carbon dioxide can be transferred into vessel 8 viamanifold 4 at 60 degrees F. to 100 degrees F. or higher or lower. Allother units shown in row 13 may apply to such carbon dioxide transferredand the mass flow can be as required to maintain sufficient volume tofill annular space 110 in FIG. 1 so that the boundary 113 of the stratumof gas is able to minimize the amount of liquid carbon dioxide thatleaves with the lean meat. It is preferable that the density of carbondioxide fluid transferred into space 110 in FIG. 1 is as low as possiblewhile maintaining sufficient pressure to enable the effectivestratification of fat and lean beef separated from ground beef asdescribed. However, it is also desirable to maintain a lower temperature(i.e., about 30 degrees F.) of the liquid carbon dioxide used in theprocess, particularly where the liquid carbon dioxide comes in contactwith the lean beef. Clearly under such circumstances a conflict canarise between lower gas density and low liquid temperature, however, gasin space 110 can be maintained at the lowest density possible, while thedensity of fluid carbon dioxide in space 118 and elsewhere in thecentrifuge system, can be maintained at the density, which is required,while maintaining a temperature of about 30 degrees F. The method inaccordance with one embodiment of the present invention enables theseparation of a first fat stream and a second lean stream from a thirdincoming stream including a blend of ground beef and fluid carbondioxide, wherein the fluid carbon dioxide is maintained with propertiesas shown in rows 4 through 7 in Table 10, for example. A minimumquantity of carbon dioxide fluid is carried with the fat and the leanstreams through their respective extraction conduits to be subsequentlywasted by venting to atmosphere. Such venting of carbon dioxide toatmosphere will result in a further loss of moisture (water) which willhave ordinarily been extracted from the ground beef; compensation ofthis water loss is made up by the introduction of water through conduit4 (FIG. 2). The volume of gas transferred, for example, via conduit 108(FIG. 1), is sufficient to enable the displacement of liquid carbondioxide from the lean beef transferred to the cone-shaped section 109.Perforations in shaft 108 similar to the perforations 204 can beprovided at any locations in the walls of shaft 108, such as at regionsclose to conduit 195. Sufficient gaseous carbon dioxide is provided intothe central space 110 of the centrifuge, and within the boundariesdefined by the parallel broken lines 181 and 113, via any conduit so asto maintain space 110 filled with gaseous carbon dioxide in a mannerthat will allow the efficient separation of lean from fat and also theseparation of liquid carbon dioxide by displacement with the gaseouscarbon dioxide to avoid wasting liquid carbon dioxide. Any gas, such asother inert gases including nitrogen, neon, argon or any halogen gas canbe provided into space 110 as shown in FIG. 1 at a selected pressurecorresponding with the pressures shown in Table 10, so as to maintainthe space 110 filled with sufficient gas. Further, the level of oxygenwithin the centrifuge 1000 is maintained at levels lower than 2000 ppm,preferably lower than 500 ppm, and even more preferably lower than 200ppm. Such low levels of oxygen can be achieved by compacting the groundmeat at the section 146, or by providing the upstream conduits in whichthe meat travels with gas other than air. Additionally, gas introducedthrough conduit 99 in screw 108 can be vented to remove oxygen.

It should be noted that carbon dioxide gas provided into space 110 inFIG. 1 can condense into lower temperature liquid carbon dioxide.Alternatively, any carbon dioxide gas provided at a temperature abovethe temperature of the liquid carbon dioxide that comes in contact withthe lower temperature carbon dioxide will be cooled by the lowertemperature, liquid carbon dioxide and consequently the volume of thegas will be reduced if it is not replenished by additional gas at a rateequal to a volume sufficient to compensate for the reduction in volume.However, the gas itself does provide an insulating effect and can act asinsulation reducing the rate of condensing and/or the rate of volumereduction. The mass flow rate of carbon dioxide gas and fluids providedinto and extracted from any and/or all ports is maintained at theselected pressures, respectively, by way of installed valves, positivedisplacement pumps and pressure regulators provided at some or allinjection and extraction ports. While not shown in the FIGS. 1-3,positive displacement pumps, valves and pressure regulators of suitablecapacities are provided to maintain selected pressures, temperatures,and densities.

The size of particles comprising the ground beef can be selected byinserting a properly sized grinding plate 148, shown in FIG. 1. The sizeof the grinding plate 148 apertures can be arranged such that theminimum quantity of lean beef is carried with the fat, and also so thatthe minimum quantity of fat is retained in the lean beef. In order toachieve the most efficient system of lean beef separation from high fatground beef, a two stage process can be arranged. In such process, agrinding plate aperture having a size of between ¼″ and up to 1″diameter or even more can be used to grind boneless beef in a firstgrinding operation. Following such coarse grinding and separating ofvery high lean content beef in a first stream, a second fat streamcontaining a quantity of lean, such as a quantity equal to 10% or even20% by weight of the fat stream, can then be ground using a grindingplate having apertures of 1/16″ diameter up to ¼″ diameter, or as may bedetermined to be an optimum grind plate size for a second stageprocessing operation. This second stage operation may be described as afine ground stream which can then be processed through the centrifugeequipment as described in connection with FIGS. 1-3, such that, in thissecond or final stage, only fat is extracted in the fat stream and thelean stream may then be combined with other ground beef. If required,the fat stream derived in the “final” stage can be processed in afurther stage by grinding via an even finer grind plate aperture size,such as 1/32″ diameter, followed by processing according to theseparation process as described herein.

In one alternate embodiment, a selected and proportioned quantity ofwater optionally containing a quantity of a salt, such as sodiumchlorite, may also be blended with the meat and liquid carbon dioxide.The amount of sodium chlorite salt added can be that amount required toprovide 500 parts per million (ppm) to 1.2% or more in solution. Anyother salts or additives may be included in the mixture, however, sodiumchlorite is a preferred salt since an anti-microbial effect can beachieved with such a blend. In addition, liquid carbon dioxide,maintained at a pressure of approximately 500 psi to 750 psi, and at atemperature of 29.5 degrees F. to 36 degrees F., when combined withsufficient water, can create a pH value of about 2.9, which is adequateto react with sodium chlorite, wherein the combined quantity is commonlyknown as acidified sodium chlorite which has anti-microbial propertiescapable of reducing bacteria content by several logs. Furthermore, theaddition of sodium chlorite can be added in such proportions so as toadjust the density of the liquid carbon dioxide which can be utilized toenhance the separation of fat from lean. For example, the specificgravity of liquid carbon dioxide at about 725 psi and 32 degrees F. isabout 0.94 and the addition of, for example, 3% water containing sodiumchlorite of 1200 ppm can increase the specific gravity of the liquidcarbon dioxide to a little under 0.95. At such specific gravity, whereinthe fluid comprises liquid carbon dioxide and a solution of sodiumchlorite in water, white fat will float quite readily. However at aspecific gravity of 0.93, such white fat may tend to sink and provedifficult to separate from the lean beef.

TABLE 10 Density lbs/cu′ Temp Pressure Vol. cu′/lb. Solid or Row ° F.psia psig Vapor Liquid 1 0 305.8 291.1 0.2906 63.64 2 28 476.6 461.90.1783 58.78 3 30 490.8 476.1 0.1722 58.4 4 32 505.5 490.8 0.1663 58.025 34 520.5 505.8 0.1602 57.59 6 36 536 521.3 0.1542 57.12 7 38 551.7 5370.1482 56.7 8 40 567.7 553 0.1425 56.29 9 42 569.3 569.3 0.1372 55.89 1050 652.9 638.2 0.1181 53.91 11 56 708.6 693.9 0.1054 52.37 12 60 747.6732.9 0.09752 51.17 13 66 809.3 794.6 0.1372 49.08 14

While the preferred embodiment of the invention has been illustrated anddescribed, it will be appreciated that various changes can be madetherein without departing from the spirit and scope of the invention.

The invention claimed is:
 1. A method for separating meat components,comprising: combining fat solids and lean meat solids with a fluidcomprising water; centrifugally spinning the fluid by centrifuge;individually separating the fat solids and lean meat solids from thefluid, wherein the fat solids, the lean meat solids, and the fluid areseparated in the same centrifuge; controlling the temperature of thelean meat solids before separating; and controlling the temperature ofseparated fluid.
 2. The method of claim 1, wherein the water comprises asalt.
 3. The method of claim 1, wherein the temperature of the fatsolids is controlled in a plate heat exchanger.
 4. The method of claim1, wherein before combining with the fluid, the fat solids are finelyground.
 5. The method of claim 1, wherein the separated fat solids arecombined with beef.
 6. The method of claim 1, wherein the fluid furthercomprises carbon dioxide.
 7. The method of claim 1, further comprisingintroducing sodium chlorite to inactivate bacteria.
 8. The method ofclaim 1, wherein the oxygen content in the centrifuge is kept below 500ppm.
 9. The method of claim 1, further comprising feeding the centrifugethrough a distributor having two oppositely disposed outlets.